It souldn’t be too hard for anyone with Photoshop or any other image manipulation program with a cloning tool. Here’s one tutorial for Photoshop, Here’s another, for GIMP.
I would take it to a local photo lab. You’d probably get better results with a professional (as opposed to a Walgreens or what have you). They can scan it at amazingly high resolutions too.
Your welcome. And regardless of what you do at least you have a couple starting points. The high resolution sofware that they have at labs is pretty amazing and I think it’s a fairly simple fix. FYI- that was done with free software. Ten years ago you would have needed Photoshop.